1. Field of the Invention
This invention relates generally to data sampling techniques and, more particularly, to improving the effective sampling rate of sensor data using Equivalent Time Sampling, and using the improved-resolution data for fault diagnosis and control purposes.
2. Discussion of the Related Art
Automobiles and other complex systems make extensive use of data acquisition using a variety of sensors. The sensor data is then used for classical feedback control, fault diagnosis, supervisory control, and other purposes. A problem which is commonly encountered is that the sensor data cannot be provided at a high enough sampling rate to accurately characterize the parameter being measured. For example, if cylinder pressure is being measured in an automotive internal combustion engine, many data points are needed during each engine stroke in order to depict the rapid changes in pressure during compression, combustion, expansion, and exhaust. Yet, with an engine capable of running at high speed, it may not be possible or practical to obtain pressure sensor data at a high enough rate. This could be due to limitations of the sensor itself, or limitations of analog-to-digital converters, circuitry, other components, or a combination thereof.
One solution to the need for high-sampling-rate data is to increase the sampling rate of all data acquisition sensors and systems. However, given the large number of sensors used in vehicles and other complex systems, this would be a very costly solution. It would be preferable to use existing low-sampling-rate sensors, but manipulate the data such that it meets the needs of high-sampling-rate diagnostic and control applications. Such a technique would enable the benefits of the diagnostic and control applications, without the added expense and complexity of high-sampling-rate sensors and circuitry.